It is known to use sterile containers usually adapted to be equipped/filled with surgical instruments intended for sterilization in medicine and especially in surgery. During the sterilizing operation the instruments are retained in the sterile container and are strongly heated at a particular temperature until microorganisms and the spores thereof possibly occurring on the surgical instruments have been killed. For ensuring and indicating to a user, such as the staff members who intend to utilize the sterile instruments in the operating theater, that the instruments have in fact completed a sterilizing operation and the use thereof constitutes no problem for a patient with respect to any risk of infection in prior art various embodiments of sterilization indicators for sterile containers have already been suggested.
From DE 33 16 141 A1, for example, an exclusively manually operable sterilization indicator is known in the form of a closure seal for a sterile container. The closure seal which is allowed to be accessed only by a defined group of persons indicates in its integer state attached to the sterile container that sterilized objects, especially surgical instruments, are provided within the sterilization container. However, it is a drawback of this type of sterilization indicator that the closure seal has to be manually applied after the sterilizing operation, has to be checked for integrity and has to be removed again or at least destroyed before the sterile container is opened. The sterilizing operation itself has to be accurately monitored for reliable assessment of the sterility by virtue of the manual application of the closure seal. In other words, the closure seal informs about the fact that the content of the sterile container underwent a sterilizing process. It cannot be inferred from the closure seal itself, however, whether the sterilizing process has been carried out in a correct and thus successful manner.
A different type of sterilization indicator is known from EP 0 412 571 B1, for example. There an (intelligent) sterilization indicator for a sterile container is described which comprises an indicating element for indicating completed sterilization of the content of the sterile container. For this purpose, the indicating element includes a spring made of memory alloy which exhibits spring tension when reaching or exceeding a predetermined temperature, preferably the sterilization temperature (>90° C.). A locking member is automatically transferred (without manual activity) by the suddenly applied spring tension to a closing position in which it is evident that sterilization has taken place (quantity reference function) and has also been carried out correctly (quality reference function).
It is a drawback, however, that a comparatively cost-intensive memory-alloyed coil spring (shape-memory element) is used for the sterilization indicator so that the spring has to be used several times. It has turned out, however, that the known spring cannot be brought into the tension-loaded memory position as often as required, but is subjected to considerable limitations regarding its service life and thus also regarding the possible sterilizing operations of the sterile container. The known sterilization indicator also turns out to constitute a problem to the effect that it is based on the principle of a comparatively inaccurate/inertly reacting rotary spring system that performs a circular actuating movement. This may result in wrong indications. Finally the sterilization indicator of EP 0 412 571 B1 has to be manually reset to its opening position when the sterile container is opened. Unless this is done, a subsequent sterilizing process cannot be documented as to quality any more.